Commonly, snail wires provided on a ring frame produce inherent or unique vibrations when they are brought into contact with the spinning yarns i.e. yarns being spun. For detecting the yarn breakage in the ring frame through detection of such vibrations as described above, there has conventionally been proposed a yarn breakage detector in which piezo-electric elements are attached to the snail wires for deriving necessary signals therefrom.
On the other hand, in ring frames or similar spinning machines, early detection of yarn breakage is of vital importance to increase the production, minimize faulty yarns, and prevent various problems in advance.
For the above purpose, there have been already known various yarn breakage detecting means, which may be classified into such types as utilizing variations due to yarn breakage by contacting a feeler with the spinning yarns, employing a photoelectric tube, or based on dielectric constant, etc. Meanwhile, the detecting means as described above are broadly divided into one kind in which the yarn breakage portions are detected while detectors are being moved along a large number of spinning yarn lines, and the other kind in which counterparts of the detectors are provided on individual spinning parts.
However, the former or moving type requires a device for moving and guiding the detectors, and, in particular, a considerable investment for applying the detectors to the existing frames. Therefore, the latter type in which the counterparts are disposed on the individual spinning parts is preferable. Furthermore, the above described photoelectric tube type or dielectric constant type is not only expensive, but is not suitable for practical applications, since improper decisions may result from accumulation of flies, etc. Moreover, it is almost impractical to dispose the detectors on the individual spinning parts from an economic point of view. Accordingly, there is a requirement for the detecting means which may be disposed on the individual spinning parts, and yet, readily applicable to the existing frames.
On the other hand, snail wires are disposed on such ring frames for guiding spinning yarns onto take-up bobbins, and produce vibrations when coming into contact with the spinning yarns, and therefore, there has also been proposed means for detecting the yarn breakage through detection of such vibrations by a piezo-electric element. Furthermore, since the above vibrations include those due to contact with the spinning yarns, and those arising from mechanical vibrations of the ring frame, there is also known another arrangement which discriminates these vibrations for detection.
For example, in the yarn breakage detecting device of U.S. Pat. No. 4,254,613 filed May 16, 1979, as shown in FIGS. 1 to 7, the spinning yarn Y is drawn out from between front rollers 1, 1', and is wound onto a bobbin 8 while being guided by a snail wire 2. Meanwhile, the spinning yarn Y is wound onto the bobbin 8 through a ring 5 supported by a ring rail 4 for simultaneous vertical movements therewith and a traveller 6 movably mounted on the ring 5, so as to form a cop 7, with an antinode ring 9 being further provided as shown. Each snail wire 2 is mounted on a lappet 3, which is, in turn, disposed on a lappet bar 10. The snail wire 2 is attached to the lappet 3 so that the position of its yarn guide portion may be changed, while the lappet bar 10 is so provided as to be vertically movable by a slight distance along a support spindle of the bobbin 8. For the detection of yarn breakage, a piezo-electric element 12 is fixed to a portion of the snail wire 2 for deriving electrical power produced in the piezo-electric element for effecting the individual detection. Meanwhile, by contact with the spinning yarn Y, the snail wire is subjected to vibrations at high frequencies, which also include the mechanical vibrations of the frame in the range of approximately 5 to 15 KHz, and thus, the snail wire is actually subjected to the vibrations as large as about 15 KHz. In connection with the above, it has been further found that the above vibrations are those inherent in the snail wire, and are not much influence by the contact pressure with respect to the spinning yarn Y or the running speed of the spinning yarn Y. Accordingly, in the present invention, it is intended to detect the yarn breakage by distinguishing the above inherent vibrations from the mechanical vibrations, through detection. For the purpose of deriving the electromotive force of the piezo-electric element 12, as shown in FIG. 2, the snail wire 2, lappet 3 and signal transmission means are mounted on the lappet bar 10, with the lappet 3 being fixed to said lappet bar 10 through an insulating plate 16 and a wiring board 15 provided at the rear face side thereof. Moreover, the lappet 3 is hingedly mounted on a lappet bracket 13, while the snail wire 2 is adjustably provided at the front face side thereof for projection or retraction as desired. As shown in FIG. 4, the piezo-electric element 12 is fixed. by a bonding material, to one flattened side of the snail wire 2. It is preferable that the snail wire 2 is elastically supported by a holder 21 through an elastic or resilient support material or member 11. As is seen in FIG. 5, the holder 21 is formed into a hollow tubular member, while a pair of grooves 22, 22 (the groove at the other side is not shown here) are provided in opposite side walls thereof, with lead wires of said piezo-electric element 12 being connected to corresponding electrically conductive plates 121 which are provided in said grooves 22. Such snail wire 2 as described above is formed together with the holder 21 as a replacement part.
On the other hand, in the under surface of the lappet 3, a slide hole 32 is provided to receive the holder 21 for supporting, while a U-shaped member indicated at 40 is inserted into the slide hole 32 from the rear side. The holder 21 and the U-shaped member 40 are both molded from an insulating material, and in the inner sides of projecting portions 41 of the U-shaped member 40, grooves 42 are respectively formed. The grooves 42 extend through the corresponding projecting portions 41, with openings 43 being provided at the end portions thereof. Meanwhile, into the grooves 42 and openings 43 thus formed, electrically conductive wires 46 are respectively inserted so as to extend therethrough. Each of the wires 46 is formed with a coiled portion 44, a terminal portion 14, and a contact portion 47 which is formed by being resiliently bent inwardly from the groove 42 as is most clearly seen in FIG. 5, and is arranged to be inserted, from the side of its contact portion 47, into the groove 42 and the opening 43. Moreover, into the coiled portions 44, 44, reduced diameter portions 35, 35 formed at opposite ends of a eylindrical member 34 made of an insulating material are inserted, with collar rings 36, 36 formed by a similar insulating material being further disposed at the opposite sides thereof, for insertion from the rear side of said slide hole 32. Furthermore, a stopper projection 45 extends upwardly from the rear side wall of the U-shaped member 40, so as to restrict the inserting position.
On the other hand, the bracket 13 of the lappet 3 is formed with a pair of hinge pin supporting portions 131, 131 on its rear wall, and also with lappet support arms 133, 133 extending inwardly from opposite ends thereof, with an elongated opening 132 being provided at approximately the central portion of its rear wall as shown. Meanwhile, at the rear side edge of the lappet 3, there are formed a pair of hinge shaft bearing portions 31, 31.
For assembly, the U-shaped member 40 earlier described is assembled into the slide hole 32 through insertion, while the cylindrical member 34 is disposed between the shaft support portions 131, 131 of the bracket 13, and then, a support shaft 33 is pushed into the bearing portions 31 of the lappet 3, shaft support portions 131 and cylindrical member 34 so as to extend therethrough. When the holder 21 earlier described has been inserted into the slide hole 32 of the lappet 3 thus assembled, the arrangement is provided as shown in FIG. 4, and the leads of the piezo-electric element 12 are connected to the terminal portions 14, 14 of the wires 46 through said wires.
In the case where the yarn breakage detecting lappet 3 is to be mounted on the existing lappet bar 10, it is necessary to electrically connect each of the terminals 14, 14, and to also make it possible to replace or positionally adjust the lappet 3. It should also be noted that, since many lappets 3 (i.e., close to 200 pieces in number) are provided on both sides of a ring frame, the insulating plate 16 and wiring board 15 employed therein are normally divided for 4 to 8 spindles, and therefore, these should be of the same type for convenience. It should further be noted that installing a large number of leads in the vicinity of the lappet bar 10 is disadvantageous. Accordingly, the wiring is so arranged that the signals from the individual snail wires can be respectively detected. More specifically, as shown in FIG. 3, the wiring boards 15 are so arranged as to be disposed next to each other, and for the electrical connections thereof, corresponding connecting portions provided at opposite side edges of the wiring boards are connected, while the connecting portions of the insulating plates 16 are formed by connecting plates 17, with said connecting plates 17 being provided so as to be pressed against the lappet bar 10 by the neighboring lappets. In other words, as shown in FIG. 6A (i.e. a cross sectional view taken along line (VI A--VI A in FIG. 2) and FIG. 6B (i.e. a cross sectional view taken along the line VI B--VI B in FIG. 2), with the wiring boards 15 being disposed on the lappet mounting face (front face) of the lappet bar 10, the insulating plates 16 are disposed to surround said wiring boards 15, and these members are fixed by lappet fixing bolts and nuts. It is to be noted that each bolt extended through the elongated opening 132 (FIG. 5) of the lappet bracket 13, an opening 162 formed in the insulating plate 16, a hole 151 of the wiring board 15 and a fixing hole of the lappet bar 10 so as to fix these members, and that the wiring board 15 is provided at one side face of the insulating plate through printed wiring.
The wiring board 15 disposed in the manner as described above has connecting portions 18, 18 for the terminals 14 formed at the upper portion of said fixing hole 151 for individual connection. Meanwhile, in the upper portion of the fixing hole 162 of the insulating plate 16, there is formed an elongated slot 161 so as to allow said terminals 14, 14 extending from the rear portion of the lappet 3 to pass therethrough. In other words, each of the terminals 14, 14 contacts the connecting portion 18 through the elongated slot 161 and constitutes the electrical path. For the electrical connections of the wiring boards 15, each of said wiring boards 15 is provided, at its opposite ends, with joint faces 19, 19 respectively which are formed symmetrically. On the other hand, each of the insulating plates 16 is made shorter in its length than the wiring board 15 at its opposite ends, so that the connecting portions of the wiring board 15 are spaced when the insulating plate 16 is joined to the writing plate 15, for filling such spaces by the connecting plate 17, with elastic terminals being provided at the mating face side of the connecting plate 17 so as to connect such joint faces 19, 19 with each other.
The electromotive force detecting means for the piezo-electric element 12 of the snail wire 2 constructed and mounted in the above described manner is shown by numeral 50 in FIG. 7, and so arranged that the two lead wires from the piezo-electric element 51 (12) are connected to a band amplifier 52 for selecting the earlier described inherent vibration frequency of the snail wire 2 in the signals from the piezo-electric element and subsequently amplifying said selected frequency by an amplifier 53 up to such a level as will be readily discriminated so as to convert the A.C. signal into a D.C. signal by a rectification and smoothing unit 54, while the region for the positive functioning is judged by a voltage comparator 55 for deriving a logic signal output 56.
Furthermore, since it is difficult, from the aspect of installation, to make the detecting means 50 to correspond to the individual lappets, the arrangement is so made that the detection and reporting be effected collectively. More specifically, for measuring the inherent vibrations of the piezo-electric elements 12 for the snail wires 2 provided in number close to 400 pieces per each one spinning frame, it is so arranged that the scanning thereof is made in a short period of time so as to effect the detection by transmitting signals of many A.C. signal sources onto the same bus line through scanning of shift registers.
Incidentally, for the snail wires 2 which detect the yarn breakage in the above described manner, it is required that they should sensitively produce the inherent vibrations to be generated, by the contact thereof with the spinning yarn Y, and simultaneously that their handling and maintenance are readily effected, while they are stably utilized over a long period. In other words, since it is troublesome to adjust the sensitivity of the snail wires or replace the same according to the kinds of the spinning yarns or due to alterations of the spinning conditions, such snail wires are required to be ones adaptable for various spinning yarns and spinning conditions.